Vertical jack



H. E. PAG E VERTICAL JACK May" 14, 1946.

Fiied'May 22, 19447 2 sheets-sheet 1 May 14, 1946.

H. E PAGE VERTICAL JACK Fiied May 22. 1944 2 Sheets-Sheet Q mw 85. A second check valve 81 seats towards the reservoir in passageway 6I, being urged seated by a coil spring 88; A uid passageway 10 communicates at one end with passageway 8| between check valves 81 and 68 and communicates at its other end with chamber 1| provided between the piston l and the inner end of cyl-` inder I0.

A fluid passageway is provided in the body, communicating at one end with chamber 42 and at its other end with bore 60. A pressure releasechamber 18 communicates via passageways `19, 80 with bore 60. The discharge end of the chamber 18 communicates with the reservoir through a passageway 82. A ball check valve 88 seats towards chamber 42 in chamber 18, being urged to seated position by a relatively stiif compression spring 85, which spring is of a strength capable of maintaining the ball 88 seated against worklifting pressure in chamber 42.

For releasing pressure from Ichamber 42 to lower a load, I provide a valve-actuating member 81 which is threaded into the chamber 18 so that whenrotated by the links 88 the inner end of the member 81 engages and moves ball 88 off its seat'to permit fluid to return to the reservoir.

By the construction described, it is relatively simple to so proportion the arms that the respective sines of their arcs are such that the saddle will be moved substantially perpendicular to the bed until a, predetermined height is reached,.

after which any, further movement will result in y the saddle being moved forwardly and downwardly about an arc. The latter function is advantageous inasmucnas it enables a load to be lifted substantially vertically to the desired height-say, for loading on a car or truck-after asoasie a strength only sumcient to withstand a pressme in chamber 42 great enough to lift the maximum load of which the jack is safely capable. Thus if auch load is exceeded, the spring 8l will yield and permit ball valve 88 to open and release the excess pressure.

I claim:

1. A Jack comprising a bed. a body movable longitudinally of the bed, a work-lifting arm pivotally mounted at one end on the body to swing relative thereto, a work-engaging saddle pivotally mounted on the free end ofl the arm, a second arm pivotally secured at one end to the bed and pivotally secured atf'its other end to the work-lifting arm, and means operatively associated with the body to move the latter longitudinally of the bed whereby 'to move the saddle in a plane substantially perpendicular kto the bed, said lastnamed means comprising a cylinder carried by the body, a piston reciprocally mounted in the cylinder and providing in conjunction therewith a pressure chamber. a 4piston rod secured at one end to the piston and extending throughthe chamber, means connecting the other end of the rod to the second arm, and iiuid pressuregenerating means communicating with the chamber.

2. A jack comprising a bed, a body movable longitudinally of the bed, a work-lifting arm pivotally mounted at one end on the body to swing rels.-

tive thereto, a work-engaging rsaddle pivotally mounted on the free end of the arm. a second arm pivotally secured at one end to the bed and pivotally secured at its other endy vto the work-lifting arm, and means operatively associated with the body to movethe latter longitudinally of the bed whereby to move the saddle in a plane substantially perpendicular to the bed. said last-named means comprising a cylinder carried by the body,

la piston reciprocally mountedl in the cylinder which it may be moved forwardly and downi wardly to be deposited thereon.

In operation, the device is placed so valve-actuating member 81 is operated to unseat.

ball 88 to allow return of the iiuid from chamber .42 to the reservoir.` Ball 88 and spring 8l also serve as a safety means to 'prevent `overload of the jack-that is, the spring 8l may b e made of um the. saddle is positioned under the load and the and providing in conjunction therewith a pressure chamber, a piston rod secured at one end to the piston and extending through vthe chamber, means connecting the other end of the rod to the second arm at a point spaced below the point at which the second arm ispivotally secured to the bed, and fluid pressure-generating means communicating with'the chamber.

3. A Jack comprising a bed. a carriage mounted to slide longitudinally of the bed. a cylinder secured to the carriage, a lifting arm having its inner end pivotally secured to the carriage, a second arm pivotally secured adjacent its inner end to the bedvand pivotally secured at its outer end lto the lifting arm, a piston in thecylinder and forming therewith apressure chamber, a piston rod secured at its innerv end to the piston 'and secured at its outer end to the inner end of the second arm and fluid pressure-generating means communicating with the pressure chamber, said carriage and piston being movable towards each other in response to pressure in the chamber.

:'r E. ruimt.l 

